Apparatus of this kind is disclosed in DE-OS No. 28 51 103.
With the considerable amount of electromagnetic UHF energy which is required for the crosslinking of an elastomer, the transmission of this UHF energy into the tube through which the strand of elastomer is passed presents problems. This is because considerable amount of UHF energy in millimeter, centimeter or decimeter wave length must be introduced substantially without loss into the tube which is filled under pressure with inert gas which is necessary to prevent chemical reaction on the outer face of the strand during crosslinking, but which must not be permitted to get into the electromagnetic generator for the UHF. The introduction of UHF energy into the tube without loss is required not only on the ground of saving energy but more particularly because in those places where the loss occurs there would be considerable heating with the possibility of damaging or destroying parts of the apparatus.